An Obama administration official told Senators Tuesday that some detainees at the Guantanamo Bay detention facility will most likely be held indefinitely if they pose a threat. The official spoke at a Senate Armed Services Committee hearing. The comments drew criticism from Democrats and human rights groups.

It is one of America's most controversial prisons. The Guantanamo Bay facility holds the self-proclaimed mastermind of the September 11 attacks as well as other terror suspects.

During his first week in office, President Obama signed an executive order to close the prison in January 2010.

"This is me following through on, not just a commitment I made during the campaign, but I think an understanding that dates back to our Founding Fathers, that we are willing to observe core standards of conduct," President Obama said.

President Obama's plan was to try some detainees in federal court and others in military commissions while transfering some abroad.

But at a Senate hearing, Defense Department lawyer Jeh Johnson described one group of prisoners that will remain behind bars.

"There will be at the end of the review a category of people that we in the administration believe must be retained for reasons of public safety and national security, and they're not necessarily people that we'll prosecute," Johnson said.

Johnson also said any detainee, even if acquitted, could be held indefinitely.

"And we've gone through our review period and we've made through the assessment the person is a security threat....I think it's our view that we would have the ability to detain that person," Johnson said.

Jo Becker is a Deputy Director of Human Rights Watch.

"It's taking the new administration down the same road that Bush traveled, and it's not going to end up in a better place," Becker said.

The international community criticized President Bush for holding terror suspects without trial. Some said it weakened U.S. credibility.

President Obama himself has said the U.S. must hold true to the constitution and American values.

He also said the administration would work with Congress and the courts to come up with a plan for indefinite detention.

"We will safeguard what we must to protect the American people, but we will also ensure the accountability and oversight that is the hallmark of our constitutional system," the president said.

Like President Bush before him, Mr. Obama says military commissions will try some of the detainees. But, according to the White House, information obtained under torture will not be allowed as evidence and detainees will have greater access to lawyers.

Human Rights Watch says military trials are still unacceptable.

"These commissions are fatally flawed. You can't fix them to create a credible system that is going to have legitamacy in the eyes of the world," Becker said.

229 detainees remain in Guantanamo Bay. It is unclear how many will be released, tried in court or held without trial.